Stacked chip-on-board module with edge connector

ABSTRACT

A module can include a module card and first and second microelectronic elements having front surfaces facing a first surface of the module card. The module card can also have a second surface and a plurality of parallel exposed edge contacts adjacent an edge of at least one of the first and second surfaces for mating with corresponding contacts of a socket when the module is inserted in the socket. Each microelectronic element can be electrically connected to the module card. The front surface of the second microelectronic element can partially overlie a rear surface of the first microelectronic element and can be attached thereto.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.14/156,967, filed Jan. 16, 2014, which is a divisional of U.S. patentapplication Ser. No. 13/306,203, filed Nov. 29, 2011, which claims thebenefit of the filing date of U.S. Provisional Patent Application Ser.No. 61/477,820, filed Apr. 21, 2011, the disclosures of which are herebyincorporated by reference herein. The following commonly-ownedapplications are hereby incorporated by reference herein: U.S.Provisional Patent Application Ser. Nos. 61/477,877, 61/477,883, and61/477,967, all filed Apr. 21, 2011.

BACKGROUND OF THE INVENTION

The present invention relates to stacked microelectronic assemblies andmethods of making such assemblies, and to components useful in suchassemblies.

Semiconductor chips are commonly provided as individual, prepackagedunits. A standard chip has a flat, rectangular body with a large frontface having contacts connected to the internal circuitry of the chip.Each individual chip typically is mounted in a package which, in turn,is mounted on a circuit panel such as a printed circuit board and whichconnects the contacts of the chip to conductors of the circuit panel. Inmany conventional designs, the chip package occupies an area of thecircuit panel considerably larger than the area of the chip itself.

As used in this disclosure with reference to a flat chip having a frontface, the “area of the chip” should be understood as referring to thearea of the front face. In “flip chip” designs, the front face of thechip confronts the face of a package substrate, i.e., the chip carrier,and the contacts on the chip are bonded directly to contacts of the chipcarrier by solder balls or other connecting elements. In turn, the chipcarrier can be bonded to a circuit panel through terminals overlying thefront face of the chip. The “flip chip” design provides a relativelycompact arrangement; each chip occupies an area of the circuit panelequal to or slightly larger than the area of the chip's front face, suchas disclosed, for example, in certain embodiments of commonly-assignedU.S. Pat. Nos. 5,148,265; 5,148,266; and 5,679,977, the disclosures ofwhich are incorporated herein by reference.

Certain innovative mounting techniques offer compactness approaching orequal to that of conventional flip-chip bonding. Packages which canaccommodate a single chip in an area of the circuit panel equal to orslightly larger than the area of the chip itself are commonly referredto as “chip-sized packages.”

Besides minimizing the planar area of the circuit panel occupied bymicroelectronic assembly, it is also desirable to produce a chip packagethat presents a low overall height or dimension perpendicular to theplane of the circuit panel. Such thin microelectronic packages allow forplacement of a circuit panel having the packages mounted therein inclose proximity to neighboring structures, thus reducing the overallsize of the product incorporating the circuit panel.

Various proposals have been advanced for providing plural chips in asingle package or module. In the conventional “multi-chip module,” thechips are mounted side-by-side on a single package substrate, which inturn can be mounted to the circuit panel. This approach offers onlylimited reduction in the aggregate area of the circuit panel occupied bythe chips. The aggregate area is still greater than the total surfacearea of the individual chips in the module.

It has also been proposed to package plural chips in a “stack”arrangement, i.e., an arrangement where plural chips are placed one ontop of another. In a stacked arrangement, several chips can be mountedin an area of the circuit panel that is less than the total area of thechips. Certain stacked chip arrangements are disclosed, for example, incertain embodiments of the aforementioned U.S. Pat. Nos. 5,679,977;5,148,265; and U.S. Pat. No. 5,347,159, the disclosure of which isincorporated herein by reference. U.S. Pat. No. 4,941,033, alsoincorporated herein by reference, discloses an arrangement in whichchips are stacked on top of another and interconnected with one anotherby conductors on so-called “wiring films” associated with the chips.

Despite the advances that have been made in multi-chip packages, thereis still a need for improvements in order to minimize the size andimprove the performance of such packages. These attributes of thepresent invention are achieved by the construction of themicroelectronic assemblies as described hereinafter.

BRIEF SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a module can include amodule card and first and second microelectronic elements having frontsurfaces facing a first surface of the module card. The module card canalso have a second surface and a plurality of parallel exposed edgecontacts adjacent an edge of at least one of the first and secondsurfaces for mating with corresponding contacts of a socket when themodule is inserted in the socket. Each microelectronic element can beelectrically connected to the module card. The front surface of thesecond microelectronic element can partially overlie a rear surface ofthe first microelectronic element and can be attached thereto.

In a particular embodiment, the second microelectronic element can havea plurality of chip contacts exposed at the front surface thereofprojecting beyond a lateral edge of the first microelectronic element.In one embodiment, the edge contacts can be exposed at at least one ofthe first or second surfaces of the module card. In an exemplaryembodiment, at least some of the edge contacts can be exposed at thesecond surface. In a particular embodiment, the module can also includean encapsulant covering the first and second microelectronic elementsand a portion of the module card. In one embodiment, the encapsulant canbe an overmold. In an exemplary embodiment, at least one of the firstand second microelectronic elements can include a memory storageelement. In a particular embodiment, at least one of the first andsecond microelectronic elements can include a DRAM element.

In one embodiment, the module can also include a plurality of leadsextending from chip contacts of the at least one of the first and secondmicroelectronic elements to the edge contacts. The leads can be usableto carry an address signal usable to address the memory storage elementin at least one of the first and second microelectronic elements. In aparticular embodiment, at least some of the edge contacts can be usableto carry at least one of a signal or a reference potential between therespective edge contact and each of the first and second microelectronicelements. In an exemplary embodiment, the module card can consistessentially of a material having a coefficient of thermal expansion ofless than 30 ppm/° C.

In an exemplary embodiment, the module can also include a spacerextending between the front surface of the second microelectronicelement and the first surface of the module card. The spacer can havesubstantially the same thickness in a vertical direction substantiallyperpendicular to the first surface as the first microelectronic element.In one embodiment, the module can also include a compliant dieattachment adhesive bonding the front surface of the firstmicroelectronic element to the first surface of the module card. In aparticular embodiment, the first microelectronic element can beflip-chip bonded to the module card. In an exemplary embodiment, thesecond microelectronic element can be flip-chip bonded to the modulecard.

In a particular embodiment, the module card can also include an apertureextending between the first and second surfaces. The module can alsoinclude a plurality of leads extending within the aperture from chipcontacts of at least one of the first and second microelectronicelements to the edge contacts. In one embodiment, the aperture can bealigned with the chip contacts of the at least one of the first andsecond microelectronic elements. In an exemplary embodiment, theaperture can be aligned with the chip contacts of the first and secondmicroelectronic elements. In a particular embodiment, the leads canextend along the first surface. In one embodiment, the leads can extendalong the second surface.

In one embodiment, the aperture can have a long dimension extending in adirection away from an edge of the module card. In an exemplaryembodiment, the aperture can be a first aperture, and the module cardcan also include a second aperture extending between the first andsecond surfaces. Each of the first and second apertures can be alignedwith the chip contacts of the respective first and secondmicroelectronic elements. In a particular embodiment, the module canalso include an encapsulant covering portions of the leads between thechip contacts and the module card. In one embodiment, the leads caninclude conductive elements on the module card and wire bonds extendingfrom the conductive elements to the chip contacts of the at least one ofthe first and second microelectronic elements.

In an exemplary embodiment, the leads can include conductive elements onthe module card and lead bonds extending from the conductive elements tothe chip contacts of the at least one of the first and secondmicroelectronic elements. In a particular embodiment, the plurality ofleads can extend from chip contacts of the first microelectronic elementto the edge contacts. In one embodiment, the plurality of leads canextend from chip contacts of the second microelectronic element to theedge contacts.

In a particular embodiment, the module can also include a plurality ofthird microelectronic elements. Each third microelectronic element canbe electrically connected to the module card. In an exemplaryembodiment, the plurality of third microelectronic elements can bearranged in a stacked configuration. Each of the third microelectronicelements can have a front or rear surface confronting a front or rearsurface of an adjacent one of the third microelectronic elements. In oneembodiment, the plurality of third microelectronic elements can bearranged in a planar configuration. Each of the third microelectronicelements can have a peripheral surface confronting a peripheral surfaceof an adjacent one of the third microelectronic elements. In aparticular embodiment, the second microelectronic element can includevolatile RAM, the third microelectronic elements can each includenonvolatile flash memory, and the first microelectronic element caninclude a processor configured to predominantly control transfers ofdata between an external component and the second and thirdmicroelectronic elements. In an exemplary embodiment, the secondmicroelectronic element can include a volatile frame buffer memorystorage element, the third microelectronic elements can each includenonvolatile flash memory, and the first microelectronic element caninclude a graphics processor.

In accordance with another aspect of the invention, a module can includea module card, first and second microelectronic elements, and aplurality of leads. The module card can have a first surface, a secondsurface, and a plurality of parallel exposed edge contacts adjacent anedge of at least one of the first and second surfaces for mating withcorresponding contacts of a socket when the module is inserted in thesocket. The first microelectronic element can have a rear surface facingthe first surface of the module card. The second microelectronic elementcan have a front surface facing the first surface of the module card.Each microelectronic element can be electrically connected to the modulecard. The second microelectronic element can partially overlie a frontsurface of the first microelectronic element and can be attachedthereto. The plurality of leads can extend from chip contacts of thesecond microelectronic element to the edge contacts.

In a particular embodiment, the module card can further include anaperture extending between the first and second surfaces. The pluralityof leads can extend within the aperture. In one embodiment, the secondmicroelectronic element can be flip-chip bonded to the module card. Inan exemplary embodiment, a component can include first and secondmodules as described above bonded to one another. The second surfaces ofthe module cards can face one another.

In accordance with yet another aspect of the invention, a module caninclude a lead frame, first and second microelectronic elements havingfront surfaces facing a first surface of the lead frame, and anencapsulant covering the first and second microelectronic elements and aportion of the lead frame. The lead frame can also have a second surfaceand a plurality of exposed module contacts adjacent an edge of at leastone of the first and second surfaces for mating with correspondingcontacts of a socket when the module is inserted in the socket. Eachmicroelectronic element can be electrically connected to the lead frame.The front surface of the second microelectronic element can partiallyoverlie a rear surface of the first microelectronic element and can beattached thereto.

In one embodiment, a component can include first and second modules asdescribed above bonded to one another. The second surfaces of the leadframes can face one another. In an exemplary embodiment, a system caninclude a plurality of modules as described above, a circuit panel, anda processor. The exposed contacts of the modules can be inserted into amating socket electrically connected with the circuit panel. Each modulecan be configured to transfer a number N of data bits in parallel in aclock cycle. The processor can be configured to transfer a number M ofdata bits in parallel in a clock cycle. M can be greater than or equalto N.

Further aspects of the invention can provide systems that incorporatemodules and/or components according to the foregoing aspects of theinvention, composite chips according to the foregoing aspects of theinvention, or both in conjunction with other electronic componentselectrically connected thereto. For example, the system can be disposedin and/or mounted to a single housing, which can be a portable housing.Systems according to preferred embodiments in this aspect of theinvention can be more compact than comparable conventional systems.

In accordance with still another aspect of the invention, a method offabricating a module can include providing a module card, mounting firstand second microelectronic elements onto the module card, andelectrically connecting the first and second microelectronic elements tothe module card. The module card can have a first surface, a secondsurface, and a plurality of exposed edge contacts adjacent an edge of atleast one of the first and second surfaces for mating with correspondingcontacts of a socket when the module is inserted in the socket. Frontsurfaces of the first and second microelectronic elements can face thefirst surface of the module card. The front surface of the secondmicroelectronic element can partially overlie a rear surface of thefirst microelectronic element and can be attached thereto.

In an exemplary embodiment, the module card can further include anaperture extending between the first and second surfaces. The module canalso include a plurality of leads extending within the aperture fromchip contacts of at least one of the first and second microelectronicelements to the edge contacts. In a particular embodiment, the leads caninclude conductive elements on the module card. The step of electricallyconnecting the first and second microelectronic elements to the modulecard can electrically connect the conductive elements to the chipcontacts of at least one of the first and second microelectronicelements using a bonding tool inserted through the aperture.

In one embodiment, the leads can include wire bonds extending from theconductive elements to the chip contacts. In an exemplary embodiment,the leads can include lead bonds extending from the conductive elementsto the chip contacts. In a particular embodiment, the method can alsoinclude the step of injecting an encapsulant onto the rear surfaces ofthe microelectronic elements and the first surface of the module card.In one embodiment, the encapsulant can be a first encapsulant. Themethod can also include the step of injecting a second encapsulant intothe aperture such that portions of the leads between the chip contactsand the module card are covered by the second encapsulant.

In a particular embodiment, the step of mounting first and secondmicroelectronic elements onto the module card can include applying acompliant die attachment adhesive between the first surface of themodule card and the front surface of the first microelectronic element.In an exemplary embodiment, the method can also include the step ofmounting a spacer between the front surface of the secondmicroelectronic element and the first surface of the module card. Thespacer can have substantially the same thickness in a vertical directionsubstantially perpendicular to the first surface as the firstmicroelectronic element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagrammatic sectional view of a stacked microelectronicassembly according to an embodiment of the present invention.

FIG. 1B is a bottom sectional view of the stacked assembly of FIG. 1A,taken along the line 1B-1B of FIG. 1A.

FIG. 1C is a side sectional view of the stacked assembly of FIG. 1B,taken along the line 1C-1C of FIG. 1B.

FIG. 2 is a diagrammatic sectional view of a stacked microelectronicassembly according to another embodiment having a flip-chip bondedmicroelectronic element.

FIG. 3 is a diagrammatic sectional view of a stacked microelectronicassembly according to another embodiment having a face-upmicroelectronic element.

FIG. 4 is a diagrammatic sectional view of a stacked microelectronicassembly according to another embodiment having a single window in themodule card through which wire bonds attached to two microelectronicelements extend.

FIG. 5 is a diagrammatic sectional view of a stacked microelectronicassembly according to another embodiment having lead bonds.

FIG. 6 is a diagrammatic sectional view of a stacked microelectronicassembly according to another embodiment having elongated solderconnects.

FIG. 7 is a diagrammatic sectional view of a stacked microelectronicassembly according to another embodiment having a microelectronicelement with contacts located near an edge thereof.

FIG. 8 is a variation of the bottom sectional view of the stackedassembly of FIG. 1B, in which one microelectronic elements has rows ofcentral contacts oriented substantially perpendicular to rows of centralcontacts of another microelectronic element.

FIG. 9A is a diagrammatic sectional view of a stacked microelectronicassembly according to another embodiment having a lead frame.

FIG. 9B is a bottom sectional view of the stacked assembly of FIG. 9A,taken along the line 9B-9B of FIG. 9A.

FIG. 9C is a side sectional view of the stacked assembly of FIG. 9B,taken along the line 9C-9C of FIG. 9B.

FIG. 10A is a diagrammatic top view of a stacked microelectronicassembly according to another embodiment having a plurality of stackedmicroelectronic elements, shown without an encapsulant.

FIG. 10B is a side sectional view of the stacked assembly of FIG. 10A,taken along the line 10B-10B of FIG. 10A.

FIG. 10C is a diagrammatic top view of a stacked microelectronicassembly according to another embodiment having a plurality ofmicroelectronic elements adjacent to one another.

FIG. 11 is a diagrammatic perspective view of a stacked microelectronicassembly according to another embodiment including two module cardsbonded to one another.

FIG. 12 is a schematic depiction of a system according to one embodimentincluding a plurality of modules.

FIG. 13 is a top plan view of a microelectronic element in theembodiment of FIG. 1A.

FIG. 14 is a top plan view of another microelectronic element in theembodiment of FIG. 1A.

DETAILED DESCRIPTION

With reference to FIGS. 1A through 1C, a module 10 according to anembodiment of the present invention can include a first microelectronicelement 20, a second microelectronic element 30, and a module card 40having exposed edge contacts 50. A first encapsulant 60 can cover themicroelectronic elements 20 and 30 and a portion of the module card 40.

In some embodiments, at least one of the first and secondmicroelectronic elements 20 and 30 can be a semiconductor chip, a wafer,or the like. For example, one or both of the first microelectronicelement 20 and the second microelectronic element 30 can include amemory storage element such as a DRAM. As used herein, a “memory storageelement” refers to a multiplicity of memory cells arranged in an array,together with circuitry usable to store and retrieve data therefrom,such as for transport of the data over an electrical interface. In aparticular example, the module 10 can be included in a single in-linememory module (“SIMM”) or a dual in-line memory module (“DIMM”).

The first microelectronic element 20 can have a front surface 21, a rearsurface 22 remote therefrom, and lateral edges 23 extending between thefront and rear surfaces. Electrical contacts 24 are exposed at the frontsurface 21 of the first microelectronic element 20. As described herein,the electrical contacts 24 of the first microelectronic element 20 canalso be referred to as “chip contacts.” As used in this disclosure, astatement that an electrically conductive element is “exposed at” asurface of a structure indicates that the electrically conductiveelement is available for contact with a theoretical point moving in adirection perpendicular to the surface toward the surface from outsidethe structure. Thus, a terminal or other conductive element which isexposed at a surface of a structure can project from such surface; canbe flush with such surface; or can be recessed relative to such surfaceand exposed through a hole or depression in the structure. The contacts24 of the first microelectronic element 20 are exposed at the frontsurface 21 within a central region 25 of the first microelectronicelement. For example, the contacts 24 can be arranged in one or twoparallel rows adjacent the center of the front surface 21.

The second microelectronic element 30 can have a front surface 31, arear surface 32 remote therefrom, and lateral edges 33 extending betweenthe front and rear surfaces. Electrical contacts 34 are exposed at thefront surface 31 of the second microelectronic element 30. As describedherein, the electrical contacts 34 of the second microelectronic element30 can also be referred to as “chip contacts.” The contacts 34 of thesecond microelectronic element 30 are exposed at the front surface 31within a central region 35 of the second microelectronic element. Forexample, the contacts 34 can be arranged in one or two parallel rowsadjacent the center of the front surface 31.

As seen in FIGS. 1A and 1C, the first and second microelectronicelements 20 and 30 can be stacked relative to one another. In someembodiments, the front surface 31 of the second microelectronic element30 and the rear surface 22 of the first microelectronic element 20 canface one another. At least a portion of the front surface 31 of thesecond microelectronic element 30 can overlie at least a portion of therear surface 22 of the first microelectronic element 20. At least aportion of the central region 35 of the second microelectronic element30 can project beyond a lateral edge 23 of the first microelectronicelement 20. Accordingly, the contacts 34 of the second microelectronicelement 30 can be positioned in a location projecting beyond the lateraledge 23 of the first microelectronic element 20.

The microelectronic assembly 10 can further include a module card 40having oppositely-facing first and second surfaces 41 and 42. One ormore electrically conductive contacts 44 can be exposed at the secondsurface 42 of the module card 40. The module card 40 can further includeone or more apertures such as the first aperture 45 and the secondaperture 46. As shown in FIGS. 1A and 1C, the front surfaces 21, 31 ofthe respective first and second microelectronic elements 20, 30 can facethe first surface 41 of the module card 40.

The module card 40 can be partly or entirely made of any suitabledielectric material. For example, the module card 40 may comprise arelatively rigid, board-like material such as a thick layer offiber-reinforced epoxy, such as Fr-4 or Fr-5 board. Regardless of thematerial employed, the module card 40 may include a single layer ormultiple layers of dielectric material. In a particular embodiment, themodule card 40 can consist essentially of a material having acoefficient of thermal expansion (“CTE”) of less than 30 ppm/° C.

As seen in FIG. 1, the module card 40 may extend beyond a lateral edge23 of the first microelectronic element 20 and a lateral edge 33 of thesecond microelectronic element 30. The first surface 41 of the modulecard 40 may be juxtaposed with the front surface 21 of the firstmicroelectronic element 20.

In the embodiment depicted in FIGS. 1A through 1C, the module card 40includes a first aperture 45 substantially aligned with the centralregion 25 of the first microelectronic element 20 and a second aperture46 substantially aligned with the central region 35 of the secondmicroelectronic element 30, thereby providing access to contacts 24 and34 through the respective first and second apertures. The first andsecond apertures 45 and 46 can extend between the first and secondsurfaces 41 and 42 of the module card 40. As shown in FIG. 1B, theapertures 45 and 46 can be aligned with the corresponding chip contacts24 or 34 of the respective first and second microelectronic elements 20and 30.

The module card 40 may also include electrically conductive contacts 44exposed at the second surface 42 thereof and electrically conductivetraces 55 extending between the contacts 44 and the exposed edgecontacts 50. The electrically conductive traces 55 electrically couplethe contacts 44 to the exposed edge contacts 50. In a particularembodiment, the contacts 44 can be end portions of respective ones ofthe traces 55.

In a particular embodiment, the module card 40 can have a plurality ofparallel exposed edge contacts 50 adjacent an insertion edge 43 of atleast one of the first and second surfaces 41, 42 for mating withcorresponding contacts of a socket (shown in FIG. 12) when the module 10is inserted in the socket. As shown in FIG. 1B, the insertion edge 43can be located such that each of the apertures 45 and 46 have a longdimension L extending in a direction away from the insertion edge of themodule card 40. Some or all of the edge contacts 50 can be exposed ateither or both of the first or second surfaces 41, 42 of the module card40.

The exposed edge contacts 50 and the insertion edge 43 can be sized forinsertion into a corresponding socket (FIG. 12) of other connector of asystem, such as can be provided on a motherboard. Such exposed edgecontacts 50 can be suitable for mating with a plurality of correspondingspring contacts (FIG. 12) within such socket connector. Such springcontacts can be disposed on single or multiple sides of each slot tomate with corresponding ones of the exposed edge contacts 50. In oneexample, at least some of the edge contacts 50 can be usable to carry atleast one of a signal or a reference potential between the respectiveedge contact and each of the first and second microelectronic elements20, 30.

As seen in FIGS. 1A through 1C, electrical connections or leads 70 canelectrically connect the contacts 24 of the first microelectronicelement 20 and the contacts 34 of the second microelectronic element 30to the exposed edge contacts 50. The leads 70 may include wire bonds 71and 72 and the conductive traces 55. In one embodiment, the leads 70 canbe considered to electrically connect each microelectronic element 20,30 to the module card 40. In a particular example, the leads 70 can beusable to carry an address signal usable to address a memory storageelement in at least one of the first and second microelectronic elements20, 30.

As used herein, a “lead” is a portion of or the entire electricalconnection extending between two electrically conductive elements, suchas the lead 70 comprising wire bonds 71 and a conductive trace 55 thatextends from one of the contacts 24 of the first microelectronic element20, through the first aperture 45, to one of the exposed edge contacts50.

In one example, the module 10 can include a plurality of leads 70extending within the apertures 45 and 46 from chip contacts 24 and 34 ofat least one of the first and second microelectronic elements 20 and 30to the exposed edge contacts 50. In a particular embodiment, the leads70 can include the conductive traces 55 on the module card 40 and thewire bonds 71, 72 extending from the conductive traces to the chipcontacts 24, 34 of at least one of the first and second microelectronicelements 20, 30.

As shown in FIG. 1B, the conductive traces 55 of the leads 70 can extendalong the second surface 42 of the module card 40. In a particularexample, the conductive traces 55 of the leads 70 can extend along thefirst surface 41 of the module card 40, or the conductive traces of theleads can extend along both the first and second surfaces 41, 42 of themodule card. Portions of the conductive traces 55 can extend along asurface 41 or 42 of the module card 40 in a direction approximatelyparallel to the long dimensions L of the apertures 45 and 46 from therespective contacts 24 and 34 to the exposed edge contacts 50. In aparticular embodiment, the conductive traces 55 be arranged in a patternalong a surface 41 or 42 of the module card 40 such that the length ofthe leads 70 between the respective contacts 24 and 34 and the exposededge contacts 50 can be minimized

Each of the wire bonds 71 and 72 can extend through the respective firstor second aperture 45 or 46 and can electrically couple a contactrespective 24 or 34 to a corresponding contact 44 of the module card 40.The process of forming the wire bonds 71 and 72 can include inserting abonding tool through the apertures 45, 46 to electrically connect theconductive contacts 24, 34 to corresponding conductive contacts 44 ofthe module card 40.

In a particular embodiment, each of the wire bonds 71 and 72 can be amultiple wire bond including a plurality of wire bonds orientedsubstantially parallel to one another. Such a multiple wire bondstructure including a plurality of wire bonds 71 or 72 can provideelectrically parallel conductive paths between a contact 24 or 34 and acorresponding contact 44 of the module card 40.

A spacer 12 can be positioned between the front surface 31 of the secondmicroelectronic element 30 and a portion of the first surface 41 of themodule card 40. Such a spacer 12 can be made, for example, from adielectric material such as silicon dioxide, a semiconductor materialsuch as silicon, or one or more layers of adhesive. If the spacer 12includes adhesives, the adhesives can connect the second microelectronicelement 30 to the module card 40. In one embodiment, the spacer 12 canhave substantially the same thickness T1 in a vertical direction Vsubstantially perpendicular to the first surface 41 of the module card40 as the thickness T2 of the first microelectronic element 20 betweenthe front and rear surfaces 21, 22 thereof.

In a particular embodiment, the spacer 12 can be replaced by a bufferingchip having a surface facing the first surface 41 of the module card 40.In one example, such a buffering chip can be flip-chip bonded tocontacts exposed at the first surface 41 of the module card 40. Such abuffering chip can be configured to help provide impedance isolation foreach of the microelectronic elements 20 and 30 with respect tocomponents external to the module 10.

One or more adhesive layers 14 can be positioned between the firstmicroelectronic element 20 and the module card 40, between the first andsecond microelectronic elements 20 and 30, between the secondmicroelectronic element 30 and the spacer 12, and between the spacer 12and the module card 40. Such adhesive layers 14 can include adhesive forbonding the aforementioned components of the module 10 to one another.In a particular embodiment, the one or more adhesive layers 14 canextend between the first surface 41 of the module card 40 and the frontsurface 21 of the first microelectronic element 20. In one embodiment,the one or more adhesive layers 14 can attach at least a portion of thefront surface 31 of the second microelectronic element 30 to at least aportion of the rear surface 22 of the first microelectronic element 20.

In one example, each adhesive layer 14 can be partly or entirely made ofa die attachment adhesive and can be comprised of a low elastic modulusmaterial such as silicone elastomer. In one embodiment, the dieattachment adhesive can be compliant. In another example, each adhesivelayer 14 can be entirely or partly made of a thin layer of high elasticmodulus adhesive or solder if the two microelectronic elements 20 and 30are conventional semiconductor chips formed of the same material,because the microelectronic elements will tend to expand and contract inunison in response to temperature changes. Regardless of the materialsemployed, each of the adhesive layers 14 can include a single layer ormultiple layers therein. In a particular embodiment where the spacer 12is made from an adhesive, the adhesive layers 14 positioned between thespacer 12 and the second microelectronic element 30 and the module card40 can be omitted.

The module 10 can also include a first encapsulant 60 and a secondencapsulant 65. The first encapsulant 60 can cover, for example, therear surfaces 22 and 32 of the respective first and secondmicroelectronic elements 20 and 30 and a portion of the first surface 41of the module card 40. In a particular embodiment, the first encapsulant60 can be an overmold. One or more second encapsulants 65 can coverportions of the front surfaces 21 and 31 of the respectivemicroelectronic elements 20 and 30 exposed within the respectiveapertures 45 and 46, a portion of the second surface 42 of the modulecard 40, the contacts 24, 34, and 44, and the wire bonds 71 and 72extending between the respective contacts 24 and 34 and thecorresponding contacts 44. In a particular embodiment, a secondencapsulant 65 can cover portions of the leads 70 extending between thechip contacts 24 and 34 and the module card 40.

In a process according to a particular embodiment, the first encapsulant60 can be injected onto the rear surfaces 22 and 32 of the respectivefirst and second microelectronic elements 20 and 30 and onto the firstsurface 41 of the module card 40. In a process according to one example,the second encapsulant 65 can be injected into the first and secondapertures 45, 46 such that portions of the leads 70 between the chipcontacts 24, 34 and the module card 40 are covered by the secondencapsulant.

FIG. 2 shows a variation of the embodiment described above with respectto FIGS. 1A through 1C. In this variation, a module 210 is the same asthe module 10 described above, except that the first microelectronicelement 220 is flip-chip bonded to the first surface 241 of the modulecard 240, rather than being wire-bonded to the second surface of themodule card.

Conductive contacts 224 are exposed at the front surface 221 of thefirst microelectronic element 220. The conductive contacts or chipcontacts 224 can be electrically connected to conductive contacts 247exposed at the first surface 241 of the module card 240, for example, byconductive masses 273. The conductive masses 273 can comprise a fusiblemetal having a relatively low melting temperature, e.g., solder, tin, ora eutectic mixture including a plurality of metals. Alternatively, theconductive masses 273 can include a wettable metal, e.g., copper orother noble metal or non-noble metal having a melting temperature higherthan that of solder or another fusible metal. In a particularembodiment, the conductive masses 273 can include a conductive materialinterspersed in a medium, e.g., a conductive paste, e.g., metal-filledpaste, solder-filled paste or isotropic conductive adhesive oranisotropic conductive adhesive.

Conductive traces (not shown in FIG. 2) can extend from the conductivecontacts 247 along the first surface 241 of the module card 240 toexposed edge contacts at an insertion edge of the module card such asthe insertion edge 43 shown in FIGS. 1B and 1C. As in the module 10described above, chip contacts 234 of the second microelectronic element230 can be electrically connected to corresponding conductive contacts244 of the module card 240 by wire bonds 272 extending through anaperture 246 of the module card.

Conductive traces can also extend from the conductive contacts 244 alongthe second surface 242 of the module card 240 to exposed edge contactsat an insertion edge of the module card such as the insertion edge 43shown in FIGS. 1B and 1C.

FIG. 3 shows another variation of the embodiment described above withrespect to FIGS. 1A through 1C. In this variation, a module 310 is thesame as the module 10 described above, except that the firstmicroelectronic element 320 is positioned with the rear surface 322thereof facing the first surface 341 of the module card 340 and at leasta portion of the front surface 321 thereof facing and partiallyoverlying at least a portion of the front surface 331 of the secondmicroelectronic element 330. The rear surface 322 of the firstmicroelectronic element 320 can be attached to the first surface 341 ofthe module card 340 by one or more adhesive layers such as the adhesivelayers 14 shown in FIGS. 1A and 1C. Conductive contacts 324 a and 324 b(collectively conductive contacts 324) can be exposed at the frontsurface 321 of the first microelectronic element 320. The chip contacts324 of the first microelectronic element 320 can include anyconfiguration of conductive contacts 324 a and/or 324 b.

The conductive contacts 324 a of the first microelectronic element 320can be exposed at the front surface 321 within a central region 325 ofthe first microelectronic element. For example, the contacts 324 a canbe arranged in one or two parallel rows adjacent the center of the frontsurface 321. The conductive contacts 324 a can be electrically connectedto conductive contacts 347 exposed at the first surface 341 of themodule card 340, for example, by wire bonds 371 a.

The conductive contacts 324 b of the first microelectronic element 320can be exposed at the front surface 321 near a lateral edge 323 of thefirst microelectronic element. For example, the contacts 324 b can bearranged in one or two parallel rows adjacent the lateral edge 323 ofthe first microelectronic element 320. The conductive contacts 324 b canbe electrically connected to conductive contacts 347 exposed at thefirst surface 341 of the module card 340, for example, by wire bonds 371b.

Similar to FIG. 2, conductive traces (not shown in FIG. 3) can extendfrom the conductive contacts 347 and 344 along the respective first andsecond surfaces 341, 342 of the module card 340 to exposed edge contactsat insertion edges of the module card such as the insertion edge 43shown in FIGS. 1B and 1C.

Although the embodiment shown in FIG. 3 is shown with the secondmicroelectronic element 330 being electrically connected to the modulecard 340 by wire bonds 372, in other embodiments, the secondmicroelectronic element can be electrically connected to the module cardin various other ways, including for example, lead bonds (as shown inFIG. 5) or flip-chip bonding with solder (as shown in FIGS. 6 and 7).

FIG. 4 shows another variation of the embodiment described above withrespect to FIGS. 1A through 1C. In this variation, a module 410 is thesame as the module 10 described above, except that first and secondmicroelectronic elements 410 and 420 are electrically connected to themodule card 440 by respective wire bonds 471 and 472 extending through acommon aperture 446 extending between first and second surfaces 441, 442of the module card, rather than having each microelectronic element beelectrically connected to the module card by wire bonds extendingthrough respective separate apertures of the module card.

As shown in FIG. 4, the conductive contacts 424 of the firstmicroelectronic element 420 can be exposed at the front surface 421 neara lateral edge 423 of the first microelectronic element. For example,the contacts 424 can be arranged in a row adjacent the lateral edge 423of the first microelectronic element 420. The conductive contacts 424can be electrically connected to conductive contacts 444 exposed at thesecond surface 442 of the module card 440, for example, by wire bonds471.

The conductive contacts 434 of the second microelectronic element 430can be exposed at the front surface 431 within a central region 435 ofthe second microelectronic element. For example, the contacts 434 can bearranged in a row approximately at the center of the front surface 431.The conductive contacts 434 can be electrically connected to conductivecontacts 444 exposed at the second surface 442 of the module card 440,for example, by wire bonds 472.

In the embodiment shown in FIG. 4, the module 410 can include a singlesecond encapsulant 465. For example, a second encapsulant 65 can coverportions of the front surfaces 421 and 431 of the respectivemicroelectronic elements 420 and 430 exposed within the single commonaperture 446, a portion of the second surface 442 of the module card440, the contacts 424, 434, and 444, and the wire bonds 471 and 472extending between the respective contacts 424 and 434 and thecorresponding contacts 444.

FIG. 5 shows another variation of the embodiment described above withrespect to FIGS. 1A through 1C. In this variation, a module 510 is thesame as the module 10 described above, except that the firstmicroelectronic element 520 is flip-chip bonded to the first surface 541of the module card 540 (in the same manner as in FIG. 2), and the secondmicroelectronic element 530 is electrically connected to the module card540 by lead bonds 574 a and 574 b (collectively the lead bonds 574)extending from conductive traces to the chip contacts 534 rather than bywire bonds.

As shown in FIG. 5, the conductive contacts 534 a and 534 b(collectively the conductive contacts 534) of the second microelectronicelement 530 can be exposed at the front surface 531 within a centralregion 535 of the second microelectronic element. For example, thecontacts 534 can be arranged in one or two parallel rows adjacent thecenter of the front surface 531. Some of the conductive contacts 534 acan be electrically connected to conductive contacts 544 exposed at thesecond surface 542 of the module card 540, for example, by lead bonds574 a. Others of the conductive contacts 534 b can be electricallyconnected to conductive contacts 547 exposed at the first surface 541 ofthe module card 540, for example, by lead bonds 574 b. As shown in FIG.5, the conductive contacts 544 and 547 can be conductive contactportions of the respective lead bonds 574 a and 574 b.

The process of forming the lead bonds 574 can generally be as describedin commonly assigned U.S. Pat. Nos. 5,915,752 and 5,489,749, thedisclosures of which are incorporated by reference herein. In the leadbonding process, each lead 570 can be displaced downwardly by a toolsuch as a thermosonic bonding tool into engagement with a correspondingconductive contact 534. Such a bonding tool can be inserted through theaperture 546 to electrically connect the leads 570 to the correspondingconductive contacts 534. Frangible sections of the leads 570 can bebroken during this process.

FIG. 6 shows another variation of the embodiment described above withrespect to FIGS. 1A through 1C. In this variation, a module 610 is thesame as the module 10 described above, except that the firstmicroelectronic element 620 is flip-chip bonded to the first surface 641of the module card 640 (in the same manner as in FIG. 2), and the secondmicroelectronic element 630 is flip-chip bonded to the first surface ofthe module card by conductive masses 675 extending between theconductive contacts 634 of the second microelectronic element andconductive contacts 647 exposed at the first surface of the module cardrather than by wire bonds. In a particular embodiment, the module card640 can be devoid of leads extending through apertures between the firstand second surfaces 641, 642 thereof, such as the apertures 45 and 46shown in FIG. 1A.

Similar to the module 10 described above, the conductive contacts 634 ofthe second microelectronic element 630 can be exposed at the frontsurface 631 within a central region 635 of the second microelectronicelement. For example, the contacts 634 can be arranged in one or twoparallel rows adjacent the center of the front surface 631.

The conductive masses 675 can be, for example, elongated solderconnects, solder balls, or any other material described above withreference to the conductive masses 273. Such conductive masses 675 canextend through the space between the spacer 612 and the lateral edge 623of the first microelectronic element 620 to electrically connect thesecond microelectronic element 630 with the module card 640.

FIG. 7 shows another variation of the embodiment described above withrespect to FIG. 6. In this variation, a module 710 is the same as themodule 610 described above, except that the second microelectronicelement 730 is flip-chip bonded to the first surface 741 of the modulecard 740 by conductive masses 775 extending between conductive contacts734 located adjacent a lateral edge 733 of the second microelectronicelement and conductive contacts 747 exposed at the first surface of themodule card, rather than having the conductive masses extend betweenconductive contacts exposed at the front surface of the secondmicroelectronic element within a central region of the secondmicroelectronic element.

In a particular example, the contacts 734 can be arranged in a rowadjacent the lateral edge 733 of the second microelectronic element 730,such that the contacts 734 can project beyond the lateral edge 723 ofthe first microelectronic element 720. In one embodiment, similar to themodule 610 described above, the module card 740 can be devoid of leadsextending through apertures between the first and second surfaces 741,742 thereof.

FIG. 8 shows another variation of the embodiment described above withrespect to FIG. 1B. In this variation, a module 810 is the same as themodule 10 described above, except that the rows of conductive contacts824 of the first conductive element 820 can be substantiallyperpendicular to the rows of conductive contacts 834 of the secondconductive element 830. In such an embodiment, the second aperture 846can have a long dimension L extending in a direction away from theinsertion edge 843 of the module card 840, similar to the secondaperture 46 shown in FIG. 1B. The first aperture 845 can be have a longdimension L′ extending in a direction substantially parallel to theinsertion edge 843 of the module card 840 and substantiallyperpendicular to the long dimension L of the second aperture 846.

The leads 870 can include a pattern of conductive traces 855 a that isthe same as the pattern of conductive traces 55 shown in FIG. 1B. Theleads 870 can further include an alternate pattern of conductive traces855 b extending from the conductive contacts 844 b exposed at the secondsurface 842 of the module card 840 to the exposed edge contacts 850. Ina particular embodiment, some of the conductive traces 855 b can extendaround lateral edges 848 of the first aperture 845.

FIG. 9 shows a variation of the embodiment described above with respectto FIGS. 1A through 1C. In this variation, a module 910 is the same asthe module 10 described above, except that the first and secondmicroelectronic elements 920 and 930 are mounted onto a lead frame 980rather than being mounted onto a module card such as the module card 40shown in FIG. 1A. In a particular embodiment, the front surfaces 921,931 of the first and second microelectronic elements 920, 930 can face afirst surface 981 of the lead frame 980, each microelectronic elementbeing electrically connected to the lead frame.

Examples of lead frame structures are shown and described in U.S. Pat.Nos. 7,176,506 and 6,765,287, the disclosures of which are herebyincorporated by reference herein. In general, a lead frame such as thelead frame 980 is a structure formed from a sheet of conductive metal,such as copper, that is patterned into segments including a plurality ofleads or conductive trace portions 985. In example embodiments, at leastone of the first and second microelectronic element 920, 930 can bemounted directly onto the leads, which can extend under themicroelectronic elements. In such an embodiment, contacts 924, 934 onthe microelectronic elements can be electrically connected to respectiveleads by solder balls or the like. The leads can then be used to formelectrical connections to various other conductive structures forcarrying an electronic signal potential to and from the microelectronicelements 920, 930. When the assembly of the structure is complete, whichcan include forming an encapsulation layer 960 thereover, temporaryelements such as a frame (not shown) can be removed from the leads ofthe lead frame 980, so as to form individual leads or conductive traceportions 985.

The first microelectronic element 920 can be attached to the lead frame980 by one or more adhesive layers 914 extending between the frontsurface 921 of the first microelectronic element and a first surface 981of the lead frame. Such adhesive layers 914 can be similar to theadhesive layers 14 described above with reference to FIGS. 1A through1C. The spacer 912 can be attached to the lead frame 980 be one or moreadhesive layers 914 extending between a front surface 913 of the spacerand the first surface 981 of the lead frame. At least a portion of thefront surface 931 of the second microelectronic element 930 canpartially overlie the rear surface 922 of the first microelectronicelement 920 and a rear surface 915 of the spacer 912. The front surface931 of the second microelectronic element 930 can be attached to therear surface 922 of the first microelectronic element 920 and the rearsurface 915 of the spacer 912 by one or more adhesive layers 914.

As seen in FIGS. 9A through 9C, electrical connections or leads 970 canelectrically connect the contacts 924 of the first microelectronicelement 920 and the contacts 934 of the second microelectronic element930 to the exposed module contacts 950. The leads 970 may include wirebonds 971 and 972 and conductive trace portions 985 of the lead frame980. In a particular example, the leads 970 can be usable to carry anaddress signal usable to address a memory storage element in at leastone of the first and second microelectronic elements 920, 930.

In one example, the lead frame 980 can define a first gap 945 and asecond gap 946 extending between the first surface 981 of the lead frameand a second surface 982 of the lead frame opposite the first surface.The first gap 945 can be aligned with the chip contacts 924 of the firstmicroelectronic element 920, such that the wire bonds 971 can extendbetween the chip contacts 924 and the second surface 982 of the leadframe through the first gap. The second gap 946 can be aligned with thechip contacts 934 of the second microelectronic element 930, such thatthe wire bonds 972 can extend between the chip contacts 934 and thesecond surface 982 of the lead frame through the second gap.

The module 910 can also include an encapsulant 960 that can cover thefirst and second microelectronic elements 20, 30 and a portion of thelead frame 980, such that the exposed module contacts 950 can be exposedat a lower surface 962 of an insertion portion 961 of the encapsulant.The encapsulant 960 can also cover the contacts 924, 934, and the wirebonds 971 and 972 extending between the respective contacts 924 and 934and the lead frame 980. The insertion portion 961 of the encapsulant 960can have an appropriate size and shape for mating with a correspondingsocket (shown in FIG. 12) when the module 910 is inserted in the socket.

In a particular embodiment, the module 910 can have a plurality ofparallel exposed module contacts 950 adjacent an insertion edge 983 ofat least one of the first and second surfaces 981, 982 for mating withcorresponding contacts of a socket (shown in FIG. 12) when the module910 is inserted in the socket. Some or all of the module contacts 950can be exposed at either or both of the first or second surfaces 981,982 of the lead frame 980.

FIGS. 10A and 10B show a variation of the embodiment described abovewith respect to FIG. 2. In this variation, a module 1010 is the same asthe module 210 described above, except that the module 1010 alsoincludes a stack of third microelectronic elements 1090 mounted onto themodule card 1040.

Similar to FIG. 2, the first microelectronic element 1020 is flip-chipbonded to the first surface 1041 of the module card 1040. The conductivecontacts or chip contacts 1024 of the first microelectronic element 1020can be electrically connected to conductive contacts 1047 exposed at thefirst surface 1041 of the module card 1040, for example, by conductivemasses 1073. Chip contacts 1034 of the second microelectronic element1030 can be electrically connected to corresponding conductive contacts1044 of the module card 1040 by wire bonds 1072 extending through anaperture 1046 of the module card. Conductive traces (not shown in FIGS.10A and 10B) can extend from the conductive contacts 1044 and 1047 alongthe first surface 1041 and/or the second surface 1042 of the module card1040 to exposed edge contacts 1050 at an insertion edge of the modulecard such as the edge 1043 or the edge 1043 a. As shown in FIG. 10B, theedge contacts 1050 can be exposed at the first surface 1041, the secondsurface 1042, or both surfaces.

There can be any number of third microelectronic elements 1090 in thestack, including, for example, two third microelectronic elements 1090 aand 1090 b as shown in FIG. 10B. The third microelectronic elements 1090can be connected with one another and/or with the edge contacts 1050 byany interconnection configuration. For example, the lower thirdmicroelectronic element 1090 a can be connected with contacts exposed ata surface of the module card 1040 via flip-chip bonding, wire bonds,lead bonds, or other interconnection configurations. One or more upperthird microelectronic elements 1090 b can be connected with contacts ofthe module card 1040 through conductive vias extending through the lowerthird microelectronic element 1090 a, wire bonds, lead bonds, or otherinterconnection configurations.

In an exemplary embodiment, the module 1010 can be configured tofunction as a solid state memory drive. In such an example, the firstmicroelectronic element 1020 can include a semiconductor chip configuredpredominantly to perform a logic function, such as a solid state drivecontroller, and the second microelectronic element 1030 can include amemory storage element such as volatile RAM, for example, DRAM. Thethird microelectronic elements 1090 can each include memory storageelements such as nonvolatile flash memory. The first microelectronicelement 1020 can include a special purpose processor that is configuredto relieve a central processing unit of a system such as the system 1200(FIG. 12) from supervision of transfers of data to and from the memorystorage elements included in the second microelectronic element 1030 andthe third microelectronic elements 1090. Such a first microelectronicelement 1020 including a solid state drive controller can provide directmemory access to and from a data bus on a motherboard (e.g., the circuitpanel 1202 shown in FIG. 12) of a system such as the system 1200.

In another embodiment, the module 1010 can be configured to function asa graphics module, for example, that can be plugged into a PCI expressslot of a notebook personal computer. In such an example, the firstmicroelectronic element 1020 can include a semiconductor chip configuredpredominantly to perform a logic function, such as a graphics processor,and the second microelectronic element 1030 can include a memory storageelement such as volatile RAM (e.g., DRAM) that can serve as a volatileframe buffer for computational graphics rendering. The thirdmicroelectronic elements 1090 can each include memory storage elementssuch as nonvolatile flash memory.

FIG. 10C shows a variation of the embodiment described above withrespect to FIGS. 10A and 10B. In this variation, a module 1010′ is thesame as the module 1010 described above, except that the module 1010′includes a plurality of third microelectronic elements 1090′ mountedonto the module card 1040 adjacent to one another rather than in astacked configuration. Similar to the module 1010, the thirdmicroelectronic elements 1090′ can be connected with contacts exposed ata surface of the module card 1040 by any interconnection configuration,such as flip-chip bonding, wire bonds, lead bonds, or otherinterconnection configurations. The module 1010′ can be used for similarexemplary functions as the module 1010, such as a solid state memorydrive or a graphics module.

FIG. 11 depicts a component 1100 including first and second modules 1110a and 1110 b according to any of the embodiments described above, suchas for example, the module 10 described with reference to FIGS. 1Athrough 1C. The first and second modules 1110 a, 1110 b can be bonded toone another with at least one layer 1165, such that the second surfaces1142 of the respective module cards 1140 of the modules can face oneanother. In a particular embodiment, the at least one layer 1165 can bea single common encapsulant such as the second encapsulant 65 shown inFIGS. 1A and 1B. In another example, the at least one layer 1165 can beone or more adhesive layers, similar to the adhesive layers 14 describedwith reference to FIGS. 1A through 1C.

The component 1100 can have one or more rows of parallel exposed edgecontacts 1150 adjacent an insertion edge 1143 of the component. Each ofthe first and second modules 1110 a, 1110 b can have a row of edgecontacts 1150 exposed at the first surface 1141 of the respective modulecard 1140, such that the edge contacts can be suitable for mating withcorresponding contacts of a socket (similar to the socket shown in FIG.12) when the component 1100 is inserted in the socket.

The modules and components described above with reference to FIGS. 1Athrough 10 can be utilized in construction of diverse electronicsystems, such as the system 1200 shown in FIG. 12. For example, thesystem 1200 in accordance with a further embodiment of the inventionincludes a plurality of modules or components 1206 as described above inconjunction with other electronic components 1208 and 1210.

The system 1200 can includes a plurality of sockets 1205, each socketincluding a plurality of contacts 1207 at one or both sides of thesocket, such that each socket 1205 can be suitable for mating withcorresponding exposed edge contacts or exposed module contacts of acorresponding module or component 1206. In the exemplary system 1200shown, the system can include a circuit panel or motherboard 1202 suchas a flexible printed circuit board, and the circuit panel can includenumerous conductors 1204, of which only one is depicted in FIG. 12,interconnecting the modules or components 1206 with one another.However, this is merely exemplary; any suitable structure for makingelectrical connections between the modules or components 1206 can beused.

In a particular embodiment, the system 1200 can also include a processorsuch as the semiconductor chip 1208, such that each module or component1206 can be configured to transfer a number N of data bits in parallelin a clock cycle, and the processor can be configured to transfer anumber M of data bits in parallel in a clock cycle, M being greater thanor equal to N.

In one example, the system 1200 can include a processor chip 1208 thatis configured to transfer thirty-two data bits in parallel in a clockcycle, and the system can also include four modules 1206 such as themodule 10 described with reference to FIGS. 1A through 1C, each module1206 configured to transfer eight data bits in parallel in a clock cycle(i.e., each module 1206 can include first and second microelectronicelements, each of the two microelectronic elements being configured totransfer four data bits in parallel in a clock cycle).

In another example, the system 1200 can include a processor chip 1208that is configured to transfer sixty-four data bits in parallel in aclock cycle, and the system can also include four modules 1206 such asthe component 1000 described with reference to FIG. 12, each module 1206configured to transfer sixteen data bits in parallel in a clock cycle(i.e., each module 1206 can include two sets of first and secondmicroelectronic elements, each of the four microelectronic elementsbeing configured to transfer four data bits in parallel in a clockcycle).

In the example depicted in FIG. 12, the component 1208 is asemiconductor chip and component 1210 is a display screen, but any othercomponents can be used in the system 1200. Of course, although only twoadditional components 1208 and 1210 are depicted in FIG. 12 for clarityof illustration, the system 1200 can include any number of suchcomponents.

Modules or components 1206 and components 1208 and 1210 can be mountedin a common housing 1201, schematically depicted in broken lines, andcan be electrically interconnected with one another as necessary to formthe desired circuit. The housing 1201 is depicted as a portable housingof the type usable, for example, in a cellular telephone or personaldigital assistant, and screen 1210 can be exposed at the surface of thehousing. In embodiments where a structure 1206 includes alight-sensitive element such as an imaging chip, a lens 1211 or otheroptical device also can be provided for routing light to the structure.Again, the simplified system shown in FIG. 12 is merely exemplary; othersystems, including systems commonly regarded as fixed structures, suchas desktop computers, routers and the like can be made using thestructures discussed above.

Turning to FIG. 13, the first microelectronic element 136 may be anytype of semiconductor chip. In this embodiment, the firstmicroelectronic element 136 can be a DRAM (dynamic random access memory)chip having conductive elements thereon. As shown, the surface area ofthe front surface 140 of the first microelectronic element 136 may bedivided into three regions having substantially equal widths in adirection between the first and second edges of the firstmicroelectronic element: a first outer region 1320, a second outerregion 1322, and a central region 1324 positioned between the firstouter region 1320 and second outer region 1322. For example, if thelength between the long edges is 6 microns, the respective lengths ofthe first outer, second outer, and central regions may be 2 microns. Thecentral region 1324 would therefore be positioned 2 microns from thefirst edge 144 and 2 microns from the second edge 144. In other words,the central region can be positioned in the middle third of the firstmicroelectronic element 136.

As is typical with regard to DRAM chips, the conductive elements mayinclude first bond pads 142 that extend along the central region 1324 ofthe front surface 140 of the first microelectronic element 136. Theconductive elements provide for an electrical connection between thefirst microelectronic element 136 and the first set of contacts 109positioned on the second surface 106 of the substrate 102. An adhesive101 can be used to attach the first microelectronic element 136 to thesubstrate 102.

The second microelectronic element 153 may be similar to the firstmicroelectronic element 136. A front surface 157 of the secondmicroelectronic element having bond pads thereon, faces the firstmicroelectronic element 136, such that the second microelectronicelement 153 overlies the rear surface 138 of the first microelectronicelement 136. As shown in FIG. 14, in this embodiment, the secondmicroelectronic element 153 has opposed first and second edges 161, 162and opposed third and fourth edges 163, 164 extending between the rearsurface 155 and front surface 157 of the second microelectronic element153 and adjacent first and second edges 161, 162. Conductive elements,such as bond pads 159, extend along the front surface 157 of the secondmicroelectronic element 153. In this embodiment, the secondmicroelectronic element 153 may be a semiconductor chip, such as a DRAMchip, with bond pads 159 positioned along a central region 1332 of thesecond microelectronic element 153, which is positioned between a firstouter region 1328 and a second outer region 1330. In one embodiment,bond pads 159 can extend in a direction transverse to the direction bondpads 142 on the first microelectronic element 136 extend.

A possible benefit of a module or component according to the invention,for example the module 10 described above with reference to FIGS. 1Athrough 1C, whereby a surface of the first microelectronic elementoverlies at least a portion of the rear surface of the secondmicroelectronic element can be to provide relatively short leadselectrically connecting a particular exposed edge contact (e.g., theexposed edge contact 50) a particular electrical contact (e.g., theelectrical contact 24) exposed at a front surface of a particularmicroelectronic element (e.g., the first microelectronic element 20).Parasitic capacitance can be considerable between adjacent leads,particularly in microelectronic assemblies that have high contactdensity and fine pitch. In microelectronic assemblies such as the module10 where the leads 70 can be relatively short, parasitic capacitance canbe reduced, particularly between adjacent leads.

Another possible benefit of a module or component according to theinvention as described above can be to provide similar lengths of leadssuch as the leads 70, for example, which can electrically connect datainput/output signal terminals (e.g., the exposed edge contacts 50) withelectrical contacts 24, 34 at the front surfaces of respective first andsecond microelectronic elements 20, 30. In systems such as the system1200 that can include a plurality of modules or components 1206, havingrelatively similar-length leads 70 can allow the propagation delay fordata input/output signals between each microelectronic element and theexposed edge contacts to be relatively closely matched.

Yet another possible benefit of a module or component according to theinvention as described above can be to provide similar lengths of leadssuch as the leads 70, for example, which can electrically connect sharedclock signal terminals and/or shared data strobe signal terminals (e.g.,the exposed edge contacts 50) with electrical contacts 24, 34 at thefront surfaces of respective first and second microelectronic elements20, 30. The data strobe signal terminals or the clock signal terminalsor both may have substantially the same loading and electrical pathlengths to the respective microelectronic elements 20, 30 and the pathlengths to each microelectronic element can be relatively short.

In any or all of the modules or components described in the foregoing,the rear surface of one or more of the first or second microelectronicelements can be at least partially exposed at an exterior surface of themicroelectronic assembly after completing fabrication. Thus, in theassembly described above with respect to FIGS. 1A through 1C, one orboth of the rear surfaces 22, 32 of the first and second microelectronicelements 20, 30 can be partially or fully exposed in the completedmodule 10. The rear surfaces 22, 32 can be partially or fully exposedalthough an overmold such as the first encapsulant 60, or otherencapsulating or packaging structures can contact or be disposedadjacent the microelectronic elements.

In any of the embodiments described above, the microelectronic assemblymay include a heat spreader made of metal, graphite or any othersuitable thermally conductive material. In one embodiment, the heatspreader includes a metallic layer disposed adjacent to the firstmicroelectronic element. The metallic layer may be exposed on the rearsurface of the first microelectronic element. Alternatively, the heatspreader can include an overmold or an encapsulant covering at least therear surface of the first microelectronic element.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

It will be appreciated that the various dependent claims and thefeatures set forth therein can be combined in different ways thanpresented in the initial claims. It will also be appreciated that thefeatures described in connection with individual embodiments may beshared with others of the described embodiments.

1. A module, comprising: a module card having a first surface, a secondsurface, and a plurality of parallel exposed edge contacts adjacent anedge of at least one of the first and second surfaces for mating withcorresponding contacts of a socket when the module is inserted in thesocket; first and second microelectronic elements, the firstmicroelectronic element having a rear surface facing the first surfaceof the module card, the second microelectronic element having a frontsurface facing the first surface of the module card, eachmicroelectronic element being electrically connected to the module card,the second microelectronic element partially overlying a front surfaceof the first microelectronic element and attached thereto; and aplurality of leads extending from chip contacts of the secondmicroelectronic element to the edge contacts.
 2. The module as claimedin claim 1, wherein the module card further includes an apertureextending between the first and second surfaces, the plurality of leadsextending within the aperture.
 3. The module as claimed in claim 2,wherein the aperture is a first aperture aligned with the chip contactsof the second microelectronic element, and the module card furtherincludes a second aperture extending between the first and secondsurfaces and aligned with chip contacts of the first microelectronicelement.
 4. The module as claimed in claim 1, wherein the secondmicroelectronic element is flip-chip bonded to the module card.
 5. Themodule as claimed in claim 1, wherein chip contacts of the secondmicroelectronic element are exposed within a central region of the frontsurface of the second microelectronic element.
 6. The module as claimedin claim 5, wherein chip contacts of the first microelectronic elementare exposed within a central region of the front surface of the firstmicroelectronic element.
 7. A component including first and secondmodules according to claim 1 bonded to one another, wherein the secondsurfaces of the module cards face one another.
 8. A method offabricating a module, comprising: providing a module card having a firstsurface, a second surface, and a plurality of exposed edge contactsadjacent an edge of at least one of the first and second surfaces formating with corresponding contacts of a socket when the module isinserted in the socket; mounting first and second microelectronicelements onto the module card, such that front surfaces of the first andsecond microelectronic elements face the first surface of the modulecard, and such that the front surface of the second microelectronicelement partially overlies a rear surface of the first microelectronicelement and is attached thereto; and electrically connecting the firstand second microelectronic elements to the module card.
 9. The method asclaimed in claim 8, wherein chip contacts of the second microelectronicelement are exposed within a central region of the front surface of thesecond microelectronic element.
 10. The method as claimed in claim 9,wherein chip contacts of the first microelectronic element are exposedwithin a central region of the front surface of the firstmicroelectronic element.
 11. The method as claimed in claim 8, whereinthe step of electrically connecting the first and second microelectronicelements to the module card includes flip-chip bonding at least one ofthe first and second microelectronic elements to the module card. 12.The method as claimed in claim 8, wherein the module card furtherincludes an aperture extending between the first and second surfaces,the module further comprising a plurality of leads extending within theaperture from chip contacts of at least one of the first and secondmicroelectronic elements to the edge contacts.
 13. The method as claimedin claim 12, wherein the leads include conductive elements on the modulecard, and the step of electrically connecting the first and secondmicroelectronic elements to the module card electrically connects theconductive elements to the chip contacts of at least one of the firstand second microelectronic elements using a bonding tool insertedthrough the aperture.
 14. The method as claimed in claim 13, wherein theleads include wire bonds extending from the conductive elements to thechip contacts.
 15. The method as claimed in claim 13, wherein the leadsinclude lead bonds extending from the conductive elements to the chipcontacts.
 16. The method as claimed in claim 12, wherein the aperture isa first aperture aligned with the chip contacts of the firstmicroelectronic element, and the module card further includes a secondaperture aligned with the chip contacts of the second microelectronicelement.
 17. The method as claimed in claim 16, wherein the leadsinclude first wire bonds extending through the first aperture from thechip contacts of the first microelectronic element to first conductiveelements exposed at the first surface of the module card, and the leadsinclude second wire bonds extending through the second aperture from thechip contacts of the second microelectronic element to second conductiveelements exposed at the first surface of the module card.